(1) Field of the Invention
The present invention generally relates to fuel fill systems in motor vehicles. In particular, the present invention is directed to a fuel filler neck assembly having a uniform hemmed connection between an outer funnel portion and an inner funnel portion, and a tooling assembly for and method of fabricating the uniform hemmed connection.
(2) Description of the Related Art
Fuel fill systems are found in motor vehicles such as automobiles, trucks, boats, airplanes, and the like, and serve to transfer fuel provided by a source external to the vehicle (e.g., a gas pump) to a fuel storage tank located in the vehicle. In general, fuel fill systems include a funnel assembly, called a fuel filler neck, connected to the fuel storage tank by one or more lengths of tube. The fuel filer neck receives fuel delivered from the external fuel source, and the one or more lengths of tube deliver the fuel to the fuel storage tank. A removable cap (e.g., a gas cap) is secured to the fuel filler neck to seal the fuel fill system after the fueling process.
In a typical fuel fill system, the fuel filler neck includes an outer funnel portion and an inner funnel portion. The outer funnel is generally connected to the fuel storage tank by tubing. The inner funnel typically includes threads that mate with a threaded gas cap and is sized to receive the nozzle from the external fuel source. The inner funnel is generally designed to fit snugly within the outer funnel but is usually not fastened or welded thereto. Rather, a separate flange is often welded to the end of the outer funnel to both connect the outer funnel to the vehicle and contain the inner funnel.
In other existing fuel fill systems, an attempt has been made to simplify fabrication of the fuel filler neck assembly by using a hemmed connection, i.e., the large diameter end of the outer funnel is folded over the large diameter end of the inner funnel, to join the outer and inner funnels. However, because outer funnel sidewalls generally have varying thicknesses due to an offset-expanded fabrication, the hemmed connection between the outer and inner funnels is often uneven thereby causing the inner funnel threads to be misaligned. Misalignment of the inner funnel threads is problematic because the threaded gas cap usually will not mate with the inner funnel threads unless the inner funnel threads are aligned properly.